Impeller and method for manufacturing said impeller

ABSTRACT

An impeller of metal for ventilators, pumps, fans for internal combustion engines and fans for air-conditioning equipment composed of root portions formed on the blades to form a closed ring which is engaged by the rim of a hub.

United States Patent 1191 Zlotek 1 IMPELLER AND METHOD FOR MANUFACTURING SAID IMPELLER [75] Inventor: Rudolf Zlotek, Mutters, near Innsbruck, Austria [73] Assignee: Willi Seeber, Bozen, Italy 22 Filed: Sept. 21, 1971 [2]] Appl. No.: 182,383

[30] Foreign Application Priority Data Sept. 21, 1970 Germany 2046486 [52] U.S. Cl 416/214, 416/216, 416/241 [51] Int. Cl F04d 29/34 [58] Field of Search 416/214-216, 416/218, 241 [56] References Cited UNITED STATES PATENTS 2,857,094 10/1958 Erwin 416/241X Apr. 2, 1974 3,515,501 6/1970 Palfreyman et al 416/230 X 3,616,508 11/1971 Wallett 29/156.8 2,405,146 8/1946 Huber 416/218 X 2,805,838 9/1957 Pickup 416/216 X 2,989,285 6/1961 Warnken 416/214 3,136,370 6/1964 Carlson 416/230 UX 3,282,561 11/1966 Frankel et al 416/216 3,532,438 10/1970 Palfreyman et al 416/217 X 3,532,439 10/1970 Palfreyman et al 416/230 X Primary ExaminerEverette A. Powell, Jr. Attorney, Agent, or Firm-Stevens, Davis, Miller & Mosher 57 ABSTRACT An impeller of metal-for ventilators, pumps, fans for internal combustion engines and fans for airconditioning equipment composed of root portions formed on the blades to form a closed ring which is engaged by the rim of a hub.

25 Claims, 21 Drawing Figures PATENTEDAPR 2mm 3.801.221

' SnEET 5 OF 5 In n! 8 IMPELLER AND METHOD FOR MANUFACTURING SAID IMPELLER The invention relates to an impeller made of metal, preferably light alloy, or a thermo-setting plastic or thermoplastic material, for fans, pumps and the like, especially for fans of cooling systems for internal combustion engines or for fans for air-conditioning equipment.

Such impellers are manufactured of metal, usually light alloy, or a thermo-setting or thermoplastic material in one piece. Limits are therefore set on the size of such fans. In particular in their manufacture from thermo-setting or thermoplastic synthetic resins, the development and construction of larger impellers is beset with difficulties and is moreover expensive as only small quantities are required and accordingly the necessary expensive molds are scarcely capable of being fully employed.

It is the aim of the invention to overcome these drawbacks. This is achieved according to the invention by a built-up construction for an impeller, in that root portions are formed on the blades, the root portions together forming a closed ring which is engaged by the rim of a central hub.

This also allows impellers for fans or ventilators to be made so that they are optimally designed for each par ticular purpose because the number of blades andtheir mounting angle can be varied, which has a decisive effect on the operational efficiency and the power consumption. This matching to the particular intended use is possible in the simplest way and without substantialoutlay.

In particular in impellers in which the blades are arranged so that one of the two radial edges of each blade overlaps the adjacent radial edge of'the adjacent blade as viewed axially, at least in the neighborhood of the blade roots, a further advantageous feature of the invention has been found, which is that the two radial lateral surfaces of each root portion extend in'an inclined direction, with those radial planes which are perpendicular to the general plane of the ring of blades making an acute included angle with the respective lateral surface of the root portion so that in the free condition the root portions, when placed side by side, lie on a helical line and furthermore the two radial side surfaces of each root portion each have respectively a projection standing out in the direction of the periphery of the ring of the rootportions, this projection having an extent in the peripheral direction of the ring which increases progressively from the inner surface of the respective portion towards the associated blade, and a complimentarily formed recess, in which the projection of the adjacent root portion engages, so that when all the projections and recesses of the adjacent root portions are in mutual engagement, a closed ring is formed from the helical line of blades. The projections and the associated recesses could each have a rectangular, halfround, oval, wedge-shaped or dovetail-shaped crosssection or instead of this they could each extend up to the adjacent face plane of the associated root portion, this plane being parallel to the general plane of the fan, and could have a shoulder or undercut, which is flat and perpendicular or inclined to the side faces or is of curved form.

By this construction account is taken in the simplest way of the fact that the radial side surfaces of the root portion cannot be formed as radial planes perpendicular to the general plane of the fan as the mutually overlapping arrangement of the blades prevents this. With the above-mentioned construction of the invention, it is ensured, nevertheless, that the side faces of each root portion itself, or the corresponding surfaces of the molds in the manufacture of the blades with root portions of plastics, can easily be produced. In the latter case all the blades provided with root portions, which are to be assembled together one behind another to form an impeller, are produced in one and the same mold, so the mold is fully employed and is moreover even cheaper than a mold necessary for the manufacture of a complete impeller.

According to a further feature of the invention the two radial side surfaces of each root portion could each have a key or rib or a corresponding groove extending substantially perpendicular to the rim or ring of blades. The grooves and keys may advantageously each have a rectangular, square, semi-circular, oval, dovetail or wedge-shaped cross-section.

Furthermore-it has been found advantageous if the root portions each have at least one groove on each of these two faces which are parallel to the general plane of the fan and the associated grooves of all of the root portions, when the latter are assembled together to make up a closed ring, form a continuous annular groove. The grooves may advantageously have a rectangular, square, semi-circular, oval, dovetail or wedgeshaped cross-section.

The impeller defined above can be produced according to the invention by arranging that first the blades are assembled together with their root portions forming a closed ring, whereupon the hub of thermoplastic or thermo-setting resin is injection-molded or extruded with its rim engaging around the ring. Instead of this it is however, also possible to construct the hub in two portions, which could be made of metal or a thermosetting plastic, and to connect them together for example by screws after inserting them in the central opening of the closed ring of root portions from opposite sides, so as to clamp the ring of blades tightly together.

In the embodiment of an impeller according to the invention described above, with blades which overlap at least in the neighborhood of the root portions, all the root portions with their blades form, after being assembled together, one complete tum of a helical path. If new the end two root portions of this line are snapped into each other, by slight elastic deformation of the line, there is obtained a complete ring of blades, with root portions, which holds itself together without external means and is capable of being handled before the hub is fitted.

Some embodiments of the invention are described in the following by way of example in conjunction with the accompanying drawings, in which:

FIG. 1 is a partially sectioned perspective view of a part of an impeller according to the invention;

FIG. 2 is a perspective view of part of a blade of the impeller of FIG. 1, with a root portion formed on it;

FIG. 3 is a perspective view, looking from the left in FIG. 2, of the blade with the root portion formed on it; FIGS. 4 to 9 each show a perspective view of the right hand lower corner of the blade root portion according to FIG. 2, each in a difi'erent construction according to the invention;

FIGS. to 13 each show an axial 'view of two adjacent root portions which are each only illustrated partially and show different embodiments of the keys and grooves extending in a longitudinal direction on the two mutually opposed side surfaces of the root portion of the blade;

FIGS. 14 to 19 each show a view of a side face of a root portion with the adjacent portion of the associated blade, the grooves, which are provided on both the upper and the lower faces of the root portion, being shown in a different form in each view; and

FIGS. and 21 each show a part of an axial section through an impeller according to the invention.

As will be seen from FIG. 1, the impeller according to the invention comprises a ring of blades 1 on each of which there is formed a root portion 2. The root portions 2 form a closed ring 2', which is engaged and gripped by the peripheral rim 3' of a central hub 3.

The hub 3 is made of a thermoplastic synthetic resin and is injection-molded around the ring 2' of root portions, so that the ring is securely held in the rim 3 and the blades 1 with their root portions 2 on the one hand and the hub 3 on the other hand form a rigid unit.

The blades 1 and root portions 2 are preferably also made of synthetic resin and are all produced in the same casting or injection mold, so that they can then be assembled together to produce the ring 2' which is then provided with the hub 3.

As is particularly clear from FIG. 1 in conjunction with FIGS. 2 and 3, each root portion 2 is provided on one radial side surface 4 with a groove 7 extending substantially perpendicular to the general plane of the ring of blades 1 and on the other side surface S with a key or rib 6 which likewise extends substantially perpendicular to the ring of blades. 1, so that in the assembled impeller of FIG. 1 each groove 7 is'engaged by the corresponding key or rib on the adjacent root portion 2.

The ribs or keys 6 and their associated grooves 7 have a complimentary shape, of the same cross-section. As shown in FIGS. 10 to 13 this can be square or dovetailed or semi-circular or wedge-shaped.

Furthermore each root portion 2 is provided on each plane of the ring of blades 1, with two grooves 8 which each cooperate with the corresponding grooves 8, of

the other root portions 2 forming the closed ring 2, to define a continuous annular groove. The hub 3 has corresponding inwardly directed annular projections 8' (FIGS. 20 and 21) on its rim 3 to engage in the concentric annular grooves thus formed in each face of the ring 2'.

- As shown in FIGS. 14 to 17 the grooves 8 can have arectangular, square, semi-circular, oval, dovetail or wedged-shaped cross-section, and the projections 8' on the rim 3 have a corresponding cross-section. Moreover, the two grooves 8 on each face of each root portion could be of the same depth (FIG. 18) or they could be arranged to have different depths and in particular the groove 8 which lies furthest from the blade 1 can either have a smaller (FIGS. 14 to 17) or a larger (FIG. 19) spacing from the central plane 9 of the associated I blade 1 and root portion 2 than the second groove 8 which is nearer the associated blade 1 and which ex tends to about the level of orslightly below, the edges of the blade.

Especially where the blades 1 are arranged to overlap, i.e., looking axially at the assembled impeller one of the two radial edges of each blade 1 overlaps the adjacent radial edge of the adjacent blade 1, at least in the neighborhood of the root portion 2, as is the case in the impeller shown in FIG. 1, the two radial side surfaces 4 and S of each root portion 2 then extend in an inclined direction and they make an acute angle with a radial plane, which is perpendicular to the hub 3, at the respective side of the root portion. This is particularly clear from FIGS. 1 to 3 and indeed by comparison of the position of the side surfaces 4 and 5 with the position of the rectangular recess 10 in the root portions 2, which recess 10 extends exactly in the direction of the periphery of the impeller and has side surfaces 10' perpendicular thereto and reinforcing ribs 11. The recesses 10 take axial forces in the hub 3. The recesses 10 are engaged by correspondingly shaped projections on the hub 3, which are formed for example in the manufacture of the hub 3 by molding or injecting around the ring 2' with a thermo-setting or thermoplastic material. Instead of the rectangular shape with perpendicular side surfaces 10' the recesses .10 could be of different shape and could have differently arranged or formed side surfaces 10'.

In this way we achieve the result that the blades 1 extend at their roots each fully up to the two radial edges in the associated root portion, with the side surfaces 4 and 5 of the simplest form. The latter is of particular significance on constructional grounds, regardless of whether the blades 1 and root'portions 2 are produced periphery of the ring 2' and of which the extent in the peripheral direction of the ring 2' increases progressively from the inner surface 13 of the root portion 2 to the associated blade 1. At the other radial side surface 5 of each root portion 2 there is provided a complimentary shaped recess 14, engaged by the projection 12 of the adjacent root portion 2 when the root portions 2 are assembled together to form the closed ring 2!.

When, starting from a blade 1 and root portion 2, all I the blades 1 and root portions 2 belonging to an impeller are brought together then, because of the abovementioned formation of the radial side surfaces 4 and 5 of each root portion 2, there results a line of root portions forming one turn of a helical thread. If the two root portions 2 at the two ends of the line are then snapped into each other, subjecting the line to resilient deformation, there is obtained the closed ring 2. The individual root portions 2 are securely held in it by the mutual engagement of the grooves 7 and keys 6 and of the projections 12 and recesses 14.

As shown in FIGS. 1 to 3 the projections 12 and the associated recesses 14 each extend up to the adjacent face, parallel to the plane of the ring of blades, of the associated root portion 2 and have a plane shoulder 15 or undercut l6 perpendicular to the side surfaces 4 or 5. As shown into FIGS. 8 and 9 shoulders 15 and undercut 16 could be curved or inclined instead.

In the embodiments of FIGS. 4 to 7 the projections 15 each have a rectangular, semi-circular, oval or wedge-shaped or dovetail shaped cross-section. The associated recesses 14 then also have the same shape.

In the embodiment of FIG. the hub is made up of two identical portions 3 which, after the ring 2 of root portions has been assembled, are inserted in its central opening from opposite sides and are secured and clamped together by screws 17 which are uniformly distributed around its periphery, so that the ring of blades 1 and root portions 2 is held fast. The two portions of the hub 3 could be made of metal or molded from thermo-setting synthetic resin.

In the embodiment of FIG. 21 corresponding to FIG. 1 of the closed ring 2 made up of root portions 2 with the ring of blades 1, is mounted in a one-piece hub 3, which can be manufactured by molding it around the ring 2' from a thermo-setting synthetic resin or by injection-molding it around the ring 2 from a thermoplastic synthetic resin.

What is claimed is:

1. An impeller especially for fans of cooling systems for internal combustion engines and fans of airconditioning equipment, comprising root portions formed on the blades to form a closed ring which is engaged by the rim of a hub, particularly wherein one of the two radial edges of each blade overlaps the adjacent radial edge of the adjacent blade in plan view at the ring of blades, at least in the neighborhood of the blade roots, the improvement characterized in that the two radial side faces of each root portion extend in inclined directions and each make an acute angle, with a radial plane perpendicular to the general plane of the ring of blades, at the associated side of the root portion, so that with the root portions freely in mutual engagement they lie on a line which forms one turn of a helical thread and that of the two radial side surfaces of each root portion one has a projection standing out in the direction of the periphery of the root portion ring, and having an extension in the peripheral direction of the ring which increases progressively from the inner surface of the associated root portion to the associated blade, and the other has a complimentarily formed recess in which the projection of the adjacent root portion engages, so that on mutual engagement of all projections and recesses a closed ring is formed from the said helical line.

2. An impeller according to claim 1 wherein the projections and the associated recesses each have a rectangular cross-section.

3. An impeller according to claim 1 wherein the projections and the associated recesses each have a semicircular cross-section.

4. An impeller according to claim 1 wherein the projections and the associated recess each have an oval cross-section.

5. An impeller according to claim 1 wherein the projections and the associated recesses each have a wedgeshaped cross-section.

6. An impeller according to claim 1 wherein the projections and the associated recesses each have a dovetail cross-section.

7. An impeller according to claim 1 wherein the projections and the associated recesses each extend up to the adjacent face, parallel to the ring of blades, of the associated root portion and have a flat shoulder and bottom, respectively.

8. An impeller according to claim 7 wherein the shoulder and bottom each extend substantially perpendicular to the side.

9. An impeller according to claim 7 wherein the shoulder and bottom each are inclined to the adjacent face, parallel to the ring of blades, of the associated root portion.

10. An impeller according to claim 1 wherein the projections and the associated recesses each extend up to the adjacent face, parallel to the ring of blades, of the associated root portion and have a curved shoulder and bottom, respectively.

11. An impeller according to claim 1 wherein the two radial side surfaces of each root portion each have a key or rib and a corresponding groove extending substantially perpendicular to the plane of the ring of blades.

12. An impeller according to claim 11 wherein the grooves and ribs have a rectangular cross-section.

13. An impeller according to claim 11 wherein the grooves and ribs have a square cross-section.

14. An impeller according to claim 11 wherein the grooves and ribs have a semi-circular cross-section.

15. An impeller according to claim 11 wherein the grooves and ribs have an oval cross-section.

16. An impeller according to claim 11 wherein the grooves and ribs have a dovetail cross-section.

17. An impeller according to claim 11 wherein the grooves and ribs have a wedge-shaped cross-section.

18. An impeller according to claim 1 wherein the root portions each have on each of the two faces that are parallel to the ring of blades at least one groove, so that the combined grooves of all the root portions, when the latter are assembled together to form a closed ring form a continuous annular groove.

19. An impeller according to claim 18 wherein the grooves have a rectangular cross-section.

20. An impeller according to claim 18 wherein the grooves have a square cross-section.

21. An impeller according to claim 18 wherein the grooves have a semi-circular cross-section.

22. An impeller according to claim 18 wherein the grooves have an oval cross-section.

23. An impeller according to claim 18 wherein the grooves have a dovetail cross-section.

24. An impeller according to claim l wherein the grooves have a wedge-shaped cross-section.

25. An impeller according to claim 1 wherein the root portions of the blades each have a recess on the face which is away from the blade, to receive a radial projection on the hub. 

1. An impeller especially for fans of cooling systems for internal combustion engines and fans of air-conditioning equipment, comprising root portions formed on the blades to form a closed ring which is engaged by the rim of a hub, particularly wherein one of the two raDial edges of each blade overlaps the adjacent radial edge of the adjacent blade in plan view at the ring of blades, at least in the neighborhood of the blade roots, the improvement characterized in that the two radial side faces of each root portion extend in inclined directions and each make an acute angle, with a radial plane perpendicular to the general plane of the ring of blades, at the associated side of the root portion, so that with the root portions freely in mutual engagement they lie on a line which forms one turn of a helical thread and that of the two radial side surfaces of each root portion one has a projection standing out in the direction of the periphery of the root portion ring, and having an extension in the peripheral direction of the ring which increases progressively from the inner surface of the associated root portion to the associated blade, and the other has a complimentarily formed recess in which the projection of the adjacent root portion engages, so that on mutual engagement of all projections and recesses a closed ring is formed from the said helical line.
 2. An impeller according to claim 1 wherein the projections and the associated recesses each have a rectangular cross-section.
 3. An impeller according to claim 1 wherein the projections and the associated recesses each have a semi-circular cross-section.
 4. An impeller according to claim 1 wherein the projections and the associated recess each have an oval cross-section.
 5. An impeller according to claim 1 wherein the projections and the associated recesses each have a wedge-shaped cross-section.
 6. An impeller according to claim 1 wherein the projections and the associated recesses each have a dovetail cross-section.
 7. An impeller according to claim 1 wherein the projections and the associated recesses each extend up to the adjacent face, parallel to the ring of blades, of the associated root portion and have a flat shoulder and bottom, respectively.
 8. An impeller according to claim 7 wherein the shoulder and bottom each extend substantially perpendicular to the side.
 9. An impeller according to claim 7 wherein the shoulder and bottom each are inclined to the adjacent face, parallel to the ring of blades, of the associated root portion.
 10. An impeller according to claim 1 wherein the projections and the associated recesses each extend up to the adjacent face, parallel to the ring of blades, of the associated root portion and have a curved shoulder and bottom, respectively.
 11. An impeller according to claim 1 wherein the two radial side surfaces of each root portion each have a key or rib and a corresponding groove extending substantially perpendicular to the plane of the ring of blades.
 12. An impeller according to claim 11 wherein the grooves and ribs have a rectangular cross-section.
 13. An impeller according to claim 11 wherein the grooves and ribs have a square cross-section.
 14. An impeller according to claim 11 wherein the grooves and ribs have a semi-circular cross-section.
 15. An impeller according to claim 11 wherein the grooves and ribs have an oval cross-section.
 16. An impeller according to claim 11 wherein the grooves and ribs have a dovetail cross-section.
 17. An impeller according to claim 11 wherein the grooves and ribs have a wedge-shaped cross-section.
 18. An impeller according to claim 1 wherein the root portions each have on each of the two faces that are parallel to the ring of blades at least one groove, so that the combined grooves of all the root portions, when the latter are assembled together to form a closed ring form a continuous annular groove.
 19. An impeller according to claim 18 wherein the grooves have a rectangular cross-section.
 20. An impeller according to claim 18 wherein the grooves have a square cross-section.
 21. An impeller according to claim 18 wherein the grooves have a semi-circular cross-section.
 22. An impeller according to claim 18 wherein the grooves have an oval cross-sectioN.
 23. An impeller according to claim 18 wherein the grooves have a dovetail cross-section.
 24. An impeller according to claim 19 wherein the grooves have a wedge-shaped cross-section.
 25. An impeller according to claim 1 wherein the root portions of the blades each have a recess on the face which is away from the blade, to receive a radial projection on the hub. 